The invention relates to installation of a cured-in-place liner within the interior of an existing conduit or pipeline, such as a sewer pipe, and more particularly to installation of a curable resin impregnated flexible liner while maintaining effluent flow through the conduit or passageway during most of the curing process.
It is generally well known that conduits or pipelines, particularly underground pipes, such as sanitary sewer pipes, storm sewer pipes, water lines and gas lines, that are employed for conducting fluids, frequently require repair due to fluid leakage. The leakage may be inward, from the environment into the interior or conducting part of the pipe, or outward, from the conducting part of the pipe into the surrounding environment. Leakage of this type may be due to improper initial installation of the pipe, deterioration of the pipe itself due to normal aging or to the effects of conveying corrosive or abrasive materials, cracking of the pipe or of pipe joints due to environmental conditions such as earthquakes, the movement of large vehicles or similar natural or man made vibrations, or any other such causes. Regardless of the cause, such leakage is undesirable and may result in waste of the fluid being conveyed by the pipe, damage to the surrounding environment and the possible creation of dangerous public health hazards.
Because of increasing labor and machinery costs, it has become increasingly more difficult and less economical to dig up and replace underground pipes, or portions or sections of such underground pipes, that may be leaking. As a result, various methods have been devised for the in situ repair or rehabilitation of the existing pipes, thereby avoiding the expenses and hazards associated with digging up and replacing the pipes or pipe sections. One of the more successful pipe repair or rehabilitation processes is the Insituform.RTM. Process and is described in U.S. Pat. No. 4,009,063 for METHOD OF LINING A PIPE and No. 4,064,211 for LINING OF PASSAGEWAYS, both to Eric Wood, the contents of which are incorporated herein by reference.
Briefly, in the Insituform.RTM. Process, an elongated flexible tubular liner of a felt fabric, foam or similar resin impregnable material that has been impregnated with a thermosetting synthetic catalyzed resin is installed within the existing pipe. The impregnated liner may be pulled into the conduit by a rope or cable, and a fluid impermeable inflation bladder or tube is then exerted within the liner. Generally, however, the liner is installed utilizing an inverting (or everting) process, as described in the latter patent.
The flexible tubular liners generally have a smooth layer of relatively flexible, substantially impermeable material coating the outside of the liner in its initial state. This impermeable layer ends up on the inside of the liner after the liner is inverted. As the flexible liner is installed in place within the existing pipeline, the liner is pressurized from within, preferably utilizing a fluid such as water. The water forces the liner to roll inside out in the pipeline and fills the inside of the liner pressing it radially outwardly to engage and conform to the interior surface of the pipe. The resin is then cured to form a hard, tight fitting, rigid pipe lining that effectively seals any cracks and that repairs any pipe or pipe joint deterioration in order to prevent further leakage either into or out of the pipe. The cured resin liner also serves to strengthen the existing pipe walls so as to provide added structural support.
After the liner has been everted into the passageway, heated fluid is circulated through the liner in order to cure the resin. This is usually done by pulling a so-called lay-flat hose into the everted liner by attaching it to the trailing end to carry it to the distal end of the liner. Heated water is then fed through that hose to the far end of the everted liner. A suction hose is used to return the water to the water heater.
When installing a liner, such as in the Insituform.RTM. process, it is necessary to divert or bypass the sewage which normally flows through the sewer. This is usually done by pumping the sewage through a bypass pipe which is taken to ground level, and the sewage is returned to the sewer at a position downstream of the section of the sewer pipe which is being lined. Performing this operation is expensive, difficult and risky in the case of large diameter sewers. The cost of bypass pumping in such circumstances tends to be a large proportion of the overall cost of the rehabilitation process.
The routing of the bypass pipe in itself presents a difficulty, keeping in mind that at ground level there will not only be the requirement to keep the bypass pipe clear of traffic and pedestrians, but additionally there will be equipment and apparatus at the site to perform the lining process, and the bypass pipe must be carefully positioned. A particular difficult situation arises when the bypass pipe must traverse a highway intersection. When the pipe is of small diameter, i.e. of the order of 4 to 6", it is a simple matter to provide vehicle and pedestrian ramps over the bypass pipe, but obviously if the pipe is of larger diameter, e.g. of the order of 12", this solution is not available. Some suggested alternatives have been proposed, such as bypassing around the installed tube as in U.S. Pat. No. 4,980,116 to Driver, the contents of which are incorporated here. While this suggestion is effective for some uses, it is difficult to use in many installations.
Accordingly, it is desirable to provide an improved method and apparatus for the installation of cured in place lining of a conduit or passageway which allows for flow through during most of the cure step of the installation and which overcomes these limitations. By utilizing the bladder device constructed and arrange in accordance with the invention, the difficulties of bypass pumping while curing takes place are substantially reduced.